ssfdc.c 11.7 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473
/*
 * Linux driver for SSFDC Flash Translation Layer (Read only)
 * (c) 2005 Eptar srl
 * Author: Claudio Lanconelli <lanconelli.claudio@eptar.com>
 *
 * Based on NTFL and MTDBLOCK_RO drivers
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/hdreg.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/blktrans.h>

struct ssfdcr_record {
	struct mtd_blktrans_dev mbd;
	int usecount;
	unsigned char heads;
	unsigned char sectors;
	unsigned short cylinders;
	int cis_block;			/* block n. containing CIS/IDI */
	int erase_size;			/* phys_block_size */
	unsigned short *logic_block_map; /* all zones (max 8192 phys blocks on
					    the 128MiB) */
	int map_len;			/* n. phys_blocks on the card */
};

#define SSFDCR_MAJOR		257
#define SSFDCR_PARTN_BITS	3

#define SECTOR_SIZE		512
#define SECTOR_SHIFT		9
#define OOB_SIZE		16

#define MAX_LOGIC_BLK_PER_ZONE	1000
#define MAX_PHYS_BLK_PER_ZONE	1024

#define KiB(x)	( (x) * 1024L )
#define MiB(x)	( KiB(x) * 1024L )

/** CHS Table
		1MiB	2MiB	4MiB	8MiB	16MiB	32MiB	64MiB	128MiB
NCylinder	125	125	250	250	500	500	500	500
NHead		4	4	4	4	4	8	8	16
NSector		4	8	8	16	16	16	32	32
SumSector	2,000	4,000	8,000	16,000	32,000	64,000	128,000	256,000
SectorSize	512	512	512	512	512	512	512	512
**/

typedef struct {
	unsigned long size;
	unsigned short cyl;
	unsigned char head;
	unsigned char sec;
} chs_entry_t;

/* Must be ordered by size */
static const chs_entry_t chs_table[] = {
	{ MiB(  1), 125,  4,  4 },
	{ MiB(  2), 125,  4,  8 },
	{ MiB(  4), 250,  4,  8 },
	{ MiB(  8), 250,  4, 16 },
	{ MiB( 16), 500,  4, 16 },
	{ MiB( 32), 500,  8, 16 },
	{ MiB( 64), 500,  8, 32 },
	{ MiB(128), 500, 16, 32 },
	{ 0 },
};

static int get_chs(unsigned long size, unsigned short *cyl, unsigned char *head,
			unsigned char *sec)
{
	int k;
	int found = 0;

	k = 0;
	while (chs_table[k].size > 0 && size > chs_table[k].size)
		k++;

	if (chs_table[k].size > 0) {
		if (cyl)
			*cyl = chs_table[k].cyl;
		if (head)
			*head = chs_table[k].head;
		if (sec)
			*sec = chs_table[k].sec;
		found = 1;
	}

	return found;
}

/* These bytes are the signature for the CIS/IDI sector */
static const uint8_t cis_numbers[] = {
	0x01, 0x03, 0xD9, 0x01, 0xFF, 0x18, 0x02, 0xDF, 0x01, 0x20
};

/* Read and check for a valid CIS sector */
static int get_valid_cis_sector(struct mtd_info *mtd)
{
	int ret, k, cis_sector;
	size_t retlen;
	loff_t offset;
	uint8_t *sect_buf;

	cis_sector = -1;

	sect_buf = kmalloc(SECTOR_SIZE, GFP_KERNEL);
	if (!sect_buf)
		goto out;

	/*
	 * Look for CIS/IDI sector on the first GOOD block (give up after 4 bad
	 * blocks). If the first good block doesn't contain CIS number the flash
	 * is not SSFDC formatted
	 */
	for (k = 0, offset = 0; k < 4; k++, offset += mtd->erasesize) {
		if (!mtd->block_isbad(mtd, offset)) {
			ret = mtd->read(mtd, offset, SECTOR_SIZE, &retlen,
				sect_buf);

			/* CIS pattern match on the sector buffer */
			if (ret < 0 || retlen != SECTOR_SIZE) {
				printk(KERN_WARNING
					"SSFDC_RO:can't read CIS/IDI sector\n");
			} else if (!memcmp(sect_buf, cis_numbers,
					sizeof(cis_numbers))) {
				/* Found */
				cis_sector = (int)(offset >> SECTOR_SHIFT);
			} else {
				DEBUG(MTD_DEBUG_LEVEL1,
					"SSFDC_RO: CIS/IDI sector not found"
					" on %s (mtd%d)\n", mtd->name,
					mtd->index);
			}
			break;
		}
	}

	kfree(sect_buf);
 out:
	return cis_sector;
}

/* Read physical sector (wrapper to MTD_READ) */
static int read_physical_sector(struct mtd_info *mtd, uint8_t *sect_buf,
				int sect_no)
{
	int ret;
	size_t retlen;
	loff_t offset = (loff_t)sect_no << SECTOR_SHIFT;

	ret = mtd->read(mtd, offset, SECTOR_SIZE, &retlen, sect_buf);
	if (ret < 0 || retlen != SECTOR_SIZE)
		return -1;

	return 0;
}

/* Read redundancy area (wrapper to MTD_READ_OOB */
static int read_raw_oob(struct mtd_info *mtd, loff_t offs, uint8_t *buf)
{
	struct mtd_oob_ops ops;
	int ret;

	ops.mode = MTD_OOB_RAW;
	ops.ooboffs = 0;
	ops.ooblen = OOB_SIZE;
	ops.oobbuf = buf;
	ops.datbuf = NULL;

	ret = mtd->read_oob(mtd, offs, &ops);
	if (ret < 0 || ops.oobretlen != OOB_SIZE)
		return -1;

	return 0;
}

/* Parity calculator on a word of n bit size */
static int get_parity(int number, int size)
{
 	int k;
	int parity;

	parity = 1;
	for (k = 0; k < size; k++) {
		parity += (number >> k);
		parity &= 1;
	}
	return parity;
}

/* Read and validate the logical block address field stored in the OOB */
static int get_logical_address(uint8_t *oob_buf)
{
	int block_address, parity;
	int offset[2] = {6, 11}; /* offset of the 2 address fields within OOB */
	int j;
	int ok = 0;

	/*
	 * Look for the first valid logical address
	 * Valid address has fixed pattern on most significant bits and
	 * parity check
	 */
	for (j = 0; j < ARRAY_SIZE(offset); j++) {
		block_address = ((int)oob_buf[offset[j]] << 8) |
			oob_buf[offset[j]+1];

		/* Check for the signature bits in the address field (MSBits) */
		if ((block_address & ~0x7FF) == 0x1000) {
			parity = block_address & 0x01;
			block_address &= 0x7FF;
			block_address >>= 1;

			if (get_parity(block_address, 10) != parity) {
				DEBUG(MTD_DEBUG_LEVEL0,
					"SSFDC_RO: logical address field%d"
					"parity error(0x%04X)\n", j+1,
					block_address);
			} else {
				ok = 1;
				break;
			}
		}
	}

	if (!ok)
		block_address = -2;

	DEBUG(MTD_DEBUG_LEVEL3, "SSFDC_RO: get_logical_address() %d\n",
		block_address);

	return block_address;
}

/* Build the logic block map */
static int build_logical_block_map(struct ssfdcr_record *ssfdc)
{
	unsigned long offset;
	uint8_t oob_buf[OOB_SIZE];
	int ret, block_address, phys_block;
	struct mtd_info *mtd = ssfdc->mbd.mtd;

	DEBUG(MTD_DEBUG_LEVEL1, "SSFDC_RO: build_block_map() nblks=%d (%luK)\n",
	      ssfdc->map_len,
	      (unsigned long)ssfdc->map_len * ssfdc->erase_size / 1024);

	/* Scan every physical block, skip CIS block */
	for (phys_block = ssfdc->cis_block + 1; phys_block < ssfdc->map_len;
			phys_block++) {
		offset = (unsigned long)phys_block * ssfdc->erase_size;
		if (mtd->block_isbad(mtd, offset))
			continue;	/* skip bad blocks */

		ret = read_raw_oob(mtd, offset, oob_buf);
		if (ret < 0) {
			DEBUG(MTD_DEBUG_LEVEL0,
				"SSFDC_RO: mtd read_oob() failed at %lu\n",
				offset);
			return -1;
		}
		block_address = get_logical_address(oob_buf);

		/* Skip invalid addresses */
		if (block_address >= 0 &&
				block_address < MAX_LOGIC_BLK_PER_ZONE) {
			int zone_index;

			zone_index = phys_block / MAX_PHYS_BLK_PER_ZONE;
			block_address += zone_index * MAX_LOGIC_BLK_PER_ZONE;
			ssfdc->logic_block_map[block_address] =
				(unsigned short)phys_block;

			DEBUG(MTD_DEBUG_LEVEL2,
				"SSFDC_RO: build_block_map() phys_block=%d,"
				"logic_block_addr=%d, zone=%d\n",
				phys_block, block_address, zone_index);
		}
	}
	return 0;
}

static void ssfdcr_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
{
	struct ssfdcr_record *ssfdc;
	int cis_sector;

	/* Check for small page NAND flash */
	if (mtd->type != MTD_NANDFLASH || mtd->oobsize != OOB_SIZE ||
	    mtd->size > UINT_MAX)
		return;

	/* Check for SSDFC format by reading CIS/IDI sector */
	cis_sector = get_valid_cis_sector(mtd);
	if (cis_sector == -1)
		return;

	ssfdc = kzalloc(sizeof(struct ssfdcr_record), GFP_KERNEL);
	if (!ssfdc) {
		printk(KERN_WARNING
			"SSFDC_RO: out of memory for data structures\n");
		return;
	}

	ssfdc->mbd.mtd = mtd;
	ssfdc->mbd.devnum = -1;
	ssfdc->mbd.tr = tr;
	ssfdc->mbd.readonly = 1;

	ssfdc->cis_block = cis_sector / (mtd->erasesize >> SECTOR_SHIFT);
	ssfdc->erase_size = mtd->erasesize;
	ssfdc->map_len = (u32)mtd->size / mtd->erasesize;

	DEBUG(MTD_DEBUG_LEVEL1,
		"SSFDC_RO: cis_block=%d,erase_size=%d,map_len=%d,n_zones=%d\n",
		ssfdc->cis_block, ssfdc->erase_size, ssfdc->map_len,
		DIV_ROUND_UP(ssfdc->map_len, MAX_PHYS_BLK_PER_ZONE));

	/* Set geometry */
	ssfdc->heads = 16;
	ssfdc->sectors = 32;
	get_chs(mtd->size, NULL, &ssfdc->heads, &ssfdc->sectors);
	ssfdc->cylinders = (unsigned short)(((u32)mtd->size >> SECTOR_SHIFT) /
			((long)ssfdc->sectors * (long)ssfdc->heads));

	DEBUG(MTD_DEBUG_LEVEL1, "SSFDC_RO: using C:%d H:%d S:%d == %ld sects\n",
		ssfdc->cylinders, ssfdc->heads , ssfdc->sectors,
		(long)ssfdc->cylinders * (long)ssfdc->heads *
		(long)ssfdc->sectors);

	ssfdc->mbd.size = (long)ssfdc->heads * (long)ssfdc->cylinders *
				(long)ssfdc->sectors;

	/* Allocate logical block map */
	ssfdc->logic_block_map = kmalloc(sizeof(ssfdc->logic_block_map[0]) *
					 ssfdc->map_len, GFP_KERNEL);
	if (!ssfdc->logic_block_map) {
		printk(KERN_WARNING
			"SSFDC_RO: out of memory for data structures\n");
		goto out_err;
	}
	memset(ssfdc->logic_block_map, 0xff, sizeof(ssfdc->logic_block_map[0]) *
		ssfdc->map_len);

	/* Build logical block map */
	if (build_logical_block_map(ssfdc) < 0)
		goto out_err;

	/* Register device + partitions */
	if (add_mtd_blktrans_dev(&ssfdc->mbd))
		goto out_err;

	printk(KERN_INFO "SSFDC_RO: Found ssfdc%c on mtd%d (%s)\n",
		ssfdc->mbd.devnum + 'a', mtd->index, mtd->name);
	return;

out_err:
	kfree(ssfdc->logic_block_map);
        kfree(ssfdc);
}

static void ssfdcr_remove_dev(struct mtd_blktrans_dev *dev)
{
	struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;

	DEBUG(MTD_DEBUG_LEVEL1, "SSFDC_RO: remove_dev (i=%d)\n", dev->devnum);

	del_mtd_blktrans_dev(dev);
	kfree(ssfdc->logic_block_map);
	kfree(ssfdc);
}

static int ssfdcr_readsect(struct mtd_blktrans_dev *dev,
				unsigned long logic_sect_no, char *buf)
{
	struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
	int sectors_per_block, offset, block_address;

	sectors_per_block = ssfdc->erase_size >> SECTOR_SHIFT;
	offset = (int)(logic_sect_no % sectors_per_block);
	block_address = (int)(logic_sect_no / sectors_per_block);

	DEBUG(MTD_DEBUG_LEVEL3,
		"SSFDC_RO: ssfdcr_readsect(%lu) sec_per_blk=%d, ofst=%d,"
		" block_addr=%d\n", logic_sect_no, sectors_per_block, offset,
		block_address);

	if (block_address >= ssfdc->map_len)
		BUG();

	block_address = ssfdc->logic_block_map[block_address];

	DEBUG(MTD_DEBUG_LEVEL3,
		"SSFDC_RO: ssfdcr_readsect() phys_block_addr=%d\n",
		block_address);

	if (block_address < 0xffff) {
		unsigned long sect_no;

		sect_no = (unsigned long)block_address * sectors_per_block +
				offset;

		DEBUG(MTD_DEBUG_LEVEL3,
			"SSFDC_RO: ssfdcr_readsect() phys_sect_no=%lu\n",
			sect_no);

		if (read_physical_sector(ssfdc->mbd.mtd, buf, sect_no) < 0)
			return -EIO;
	} else {
		memset(buf, 0xff, SECTOR_SIZE);
	}

	return 0;
}

static int ssfdcr_getgeo(struct mtd_blktrans_dev *dev,  struct hd_geometry *geo)
{
	struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;

	DEBUG(MTD_DEBUG_LEVEL1, "SSFDC_RO: ssfdcr_getgeo() C=%d, H=%d, S=%d\n",
			ssfdc->cylinders, ssfdc->heads, ssfdc->sectors);

	geo->heads = ssfdc->heads;
	geo->sectors = ssfdc->sectors;
	geo->cylinders = ssfdc->cylinders;

	return 0;
}

/****************************************************************************
 *
 * Module stuff
 *
 ****************************************************************************/

static struct mtd_blktrans_ops ssfdcr_tr = {
	.name		= "ssfdc",
	.major		= SSFDCR_MAJOR,
	.part_bits	= SSFDCR_PARTN_BITS,
	.blksize	= SECTOR_SIZE,
	.getgeo		= ssfdcr_getgeo,
	.readsect	= ssfdcr_readsect,
	.add_mtd	= ssfdcr_add_mtd,
	.remove_dev	= ssfdcr_remove_dev,
	.owner		= THIS_MODULE,
};

static int __init init_ssfdcr(void)
{
	printk(KERN_INFO "SSFDC read-only Flash Translation layer\n");

	return register_mtd_blktrans(&ssfdcr_tr);
}

static void __exit cleanup_ssfdcr(void)
{
	deregister_mtd_blktrans(&ssfdcr_tr);
}

module_init(init_ssfdcr);
module_exit(cleanup_ssfdcr);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Claudio Lanconelli <lanconelli.claudio@eptar.com>");
MODULE_DESCRIPTION("Flash Translation Layer for read-only SSFDC SmartMedia card");